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Save Money, Beat the HeatT&D World Magazine

Joseph S. Wigington, Morristown Utility SystemsWed, 2014-08-27 15:45

As summer winds down in most of the U.S., it is still balmy in the South. In a time of increasingly heighteneddemand for electricity, many utilities like Morristown Utility Systems (MUS) are using the opportunity toimplement advanced metering infrastructure (AMI) and demand-driven programs designed to shave peaks,reduce cost and increase operational efficiency. A multiservice utility serving nearly 15,000 electrical,12,000 water/wastewater and 5,800 telecom customers in eastern Tennessee, MUS has completeddeployment of a fiber-to-the-home (FTTH)-based TUNet AMI network and endpoints, becoming just thethird utility in the state to use FTTH for data communications.

With an AMI communications infrastructure now in place, MUS is broadening its focus on value-addprograms and applications like load management designed to improve operational performance and reducepeak demand up to 4% systemwide, thereby reducing wholesale cost.

Leading the Charge

As part of a Tennessee Valley Authority (TVA) smart grid pilot project, MUS is partnering with its generator,TVA, to curtail load at TVA’s day-ahead request for up to 100 hours per year. This initiative is part of TVA’sfive-year plan to combine energy efficiency and demand response to achieve systemwide savings goals of2.9% by 2015 and 5.4% by 2020. Eventually, this project will help to lower TVA’s overall peak demand,reduce the need for additional power plant construction and avoid the need for distributors to make costlypower purchases off the grid. The project requires MUS to perform closed-loop voltage reduction (CLVR)to deliver load reduction and operate during the period within the American National Standards Institute(ANSI) voltages limits.

MUS is one of several distributors who received funding through grants from TVA to explore new demandmanagement technologies, glean valuable lessons and help to replicate success for distributors throughoutthe Tennessee Valley. Project funds were awarded through a competitive selection process based on merit,potential value and potential cost savings to both the utility and its consumers.

In service to its customers, MUS is always looking for new ways to improve its operations and manage costs.One way the utility is demonstrating that commitment is by using CLVR to shave its own peak billeddemand. Beginning in April 2011, TVA returned to the practice of billing power distributors for theirmaximum 1-hour peak monthly demand. Like many other distributors, MUS’s peak is not coincident withTVA’s peaks, so MUS must track its own load and perform CLVR as needed to accurately predict and pay forpeak demand. Accuracy of data translates to dollars spent and saved, thus making data management andcontrol tools crucial for the utility to audit voltage status effectively and reduce thousands of dollars off itswholesale power bill.

Additionally, the introduction of real-time alarms and voltages into supervisory control and data acquisition(SCADA) opens the door for automating existing conservation voltage reduction (CVR) programs. Inpractice, the ability to port low-voltage alarms from selected meters in TUNet, the Tantalus utility network,directly into SCADA provides, for the first time, a tool for dispatchers to monitor voltage conditions acrossthe feeders in real time and respond accordingly to maintain adequate voltage. It provides an online healthcheck that monitors the pulse of the electric system.

CLVR Introduction

CLVR is one of the most simple, cost-effective ways utilities can manage loads to reduce peak electricaldemand immediately. Unlike traditional CVR, in which voltage is lowered to decrease overall annual energyconsumption, CLVR provides the utility with the capability to shift load and reduce peak demand. Bycombining AMI with SCADA, CLVR provides a way to monitor and adjust voltage on the fly automatically,maximize the effectiveness of voltage regulation efforts and maintain end-of-line voltages within regulatorylimits.

The key benefits of CLVR for utilities are as follows:

• Reduces demand charges immediately

• Serves as a virtually invisible program to the consumer

• Requires no consumer marketing programs or buy in

• Is rapidly deployable (up and running within hours)

• Maximizes the effectiveness of voltage reduction programs

• Identifies unrecognized inefficiencies in the existing power grid.

CLVR is designed to decrease a utility’s total electrical load in anticipation of a peak event by making slightreductions in the feeder voltages coming from substations. For example, on a hot summer day, when thedemand on a utility’s generation capacity is strained and approaching peak, CLVR applications acknowledgethe peak and immediately act to temporarily decrease voltage. Appliances, lighting, resistive heating andcertain types of motors will immediately draw less power yet still perform within acceptable levels. Althoughthe reduction is slight and power quality remains within adequate regulatory tolerances, the cumulativeimpact of thousands of electrical devices simultaneously using less power has a significant impact on autility’s load.

While voltage control as a means of demand management is not a new concept and has been deployed bymany utilities over the years, recent advances in the quality, automation and real-time nature of certain AMIcommunication and data management technologies have significantly multiplied the usefulness of meterdata. In turn, this has translated to increased control and power quality.

Shifting Demand

When electric demand exceeds available power, brownouts, blackouts and the need to purchase expensivewholesale power can occur. This risk makes the proactive management of such peak loads critical tomaintaining grid reliability and managing utility costs. Using AMI-enabled tools like CLVR helps the utilityto manage peak load by responding to peak reduction requests with immediately dispatchable voltagereduction commands. Furthermore, instantaneous feedback from the AMI system on the voltage impact ofCLVR provides utility decision makers with the real-time system visibility needed to make additionaldecisions to reduce overall load, if needed.

Thermostatically controlled devices provide another classic example of how CLVR can be used to shift load.With CLVR, devices such as electric heaters, heat pumps, stoves and refrigerators may run for slightlylonger periods of time to reach their desired temperatures but will also draw less power under carefullymonitored CLVR. The impact of this application during peak times results in a reduction, or smoothing, ofpeak load.

With the right real-time smart grid communications platform, CLVR can be used throughout the day tolower voltages during peak periods and increase voltages during off-peak periods. TUNet offers real-timeTRUPUSH functionality, which, when integrated with a utility’s SCADA system, proactively monitors,notifies and enables the control of feeder voltages within seconds. Continuous data feedback allowsoperators to monitor line voltages and alerts while making adjustments as necessary. The Tantalus voltagereduction application enables the utility to reduce peak electrical demand over time while ensuringcustomers’ service voltages stay inside acceptable levels.

Safety in Numbers

Properly conducted CLVR is safe for electrical equipment, which is designed to operate with some voltageflexibility in mind. In North America, end-use voltages in the range of 114 V to 126 V are standard (range A inANSI standard C84.1) and provide the variance needed for CLVR. Smart meters supported by a robust real-time communications network can monitor voltage throughout a grid to ensure levels remain within aprescribed range. As such, demand management programs like CLVR are one of many high-value benefitsoffered by a flexible, reliable smart grid communications network.

TUNet is designed in a way that supports safe, effective CLVR. With TUNet’s AMI network, each metercontinuously monitors many aspects of power. For instance, TUNet devices check line voltages several timesa second, 24 hours a day, 365 days a year. If the voltage exceeds or drops below preset levels at anyendpoint, the meter can immediately report this change in power quality by using TRUPUSH-event driven,command and control communications to push alerts and status updates in real time. The ability to managethousands of smart devices optimally on an electric grid in this manner is unprecedented historically.

The AMI Advantage

A cornerstone feature of two-way AMI is its ability to acknowledge and transmit real-time notifications. Thisfeature ensures, during a CLVR period, the utility receives real-time voltage alerts from any meter reachingits threshold. To take this a step further, integrating a voltage reduction application with SCADA systemsprovides an automated way to ensure maximized CLVR savings while maintaining reliable customer powerquality. The main advantages of automated demand management include the following:

1. Labor savings, by eliminating the need for operational personnel to monitor load continuously

2. The ability to deploy at multiple locations concurrently

3. The ability to handle unanticipated load peaks.

Demand management through voltage reduction requires little infrastructure beyond AMI and SCADA.Tantalus is continuously improving existing feature sets like its recently unveiled DNP3 interface for thedelivery of voltage alert data from selected meters to the SCADA system. Developed in conjunction with the

Efacec Advanced Control Systems SCADA system and deployed with MUS’s high-speed FiberNET, this low-latency AMI-DNP3 interface delivers voltage sag alarms to the MUS SCADA system within seconds of anydetection of a voltage event by any affected meter, including those deployed near the end of the line or atany strategic point in the distribution system.

TUNet’s real-time capability lies in the design and architecture of the hybrid-mesh 900-MHz local areanetwork, which allows timely voltage data from all of the smart meters to reach the SCADA system foroptimal decision making.

Effects and Results

MUS’s experiences in implementing a real-time demand management program have proven highly effectivefor reducing demand from the utility side without impacting the convenience of the consumer. In fact, thisbehind-the-scenes program works so seamlessly with the AMI network that customers experience nodiscernible drop in power quality while the utility is able to meet its goal of reducing system voltage by up to4% during peak.

For this program, MUS uses its ultra-high, gigabit-speed fiber network along with two-way communicatingload management devices installed at substation voltage regulators for scheduled or on-demandcurtailment. The distinctive push-type feature of the network ensures operators receive fresh dataconsistently with the ability to dial back voltage with more precision. The results of this program are verypromising with MUS already on track to realize a significant net reduction in wholesale power cost in excessof US$1.5 million since April 2011.

Because of the flexibility real-time AMI provides, MUS can use a suite of advanced metering and demandmanagement solutions while relying on a common, unified network. This advantage is clearly demonstratedby MUS’s use of various features within its demand management application suite. Not only can MUS usethe network to leverage the CLVR program, it can expand its demand management options to include themanagement of distributed generation sources, commercial and industrial applications, and utility water-pumping demand reduction as opposed to traditional constant CVR alternatives. This program allows MUSto pursue multiple business goals strategically at once while multiplying the effectiveness of their overalldemand management initiatives.

Through AMI-enabled demand management, MUS is able to address two of its primary goals:

• Implement cost saving and energy-efficient technologies to keep rates low

• Optimize operations throughout its service area.

The ability to detect situations quickly where it could reduce line voltage to the ideal level is helping makeMUS’s network more efficient and saving the utility money every day. This allows MUS to reduce its annualenergy consumption and peak load, as well as easily monitor potential system problems.

In achieving MUS’s efficiency goals over the long term, demand management programs like CLVR willcontinue to provide a wealth of knowledge to identify weaknesses and inefficiencies in the power grid. InMorristown, all voltage reduction is performed by load-tap changers at the substation transformer. Thismeans all feeders are reduced by the same percentage voltage drop so the amount of load delivered isinherently limited by the weakest feeder. MUS plans to use this and other lessons learned during CLVRevents to improve overall voltage profiles and deliver more flexibility in demand regulation.

In addition to numerous utility benefits, reducing peak demand has long-term benefits for the citizens ofMorristown. By implementing effective tools to manage peak demand, the utility is able to avoidinconvenient and dangerous brownouts and blackouts while improving service quality. Effective peakmanagement tools allow distribution utilities to reduce peak demand charges. When several utilitiesparticipate in reducing peak demand, it allows generation utilities to defer the purchase of expensive newpower plants, which works to keep rates low. CLVR is both effective and consumer friendly, making it anideal choice for utilities looking for easily implemented demand management solutions.

Acknowledgement

The author would like to thank the team at Tantalus for its partnership in making MUS’s demandmanagement program a successful means to save money and energy.

Joseph S. Wigington (jwigington@musfiber.net) is a registered professional engineer with more than 35years of experience in the utility and manufacturing industries. After positions with TVA and the BASFCorp., he joined Morristown Utility Systems in 1995 and has served as general manager since 2007. In hiscurrent role, as general manager and CEO, he is responsible for managing utility operations to providepower, water, wastewater and broadband fiber telecommunications services for the city of Morristown,Tennessee.

Mentioned in this article:

Efacec ACS | www.efacecusa.com

Itron | www.itron.com

Tantalus | www.tantalus.com

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